The present invention relates to a disc player and, particularly, to a cleaning device for cleaning a lens surface of an optical pick-up device for use in reproducing a signal recorded on a disc by irradiating it with a laser light.
It is well known that music recorded together with a control signal on a disc referred to as a compact disc is reproduced by irradiating the disc with a laser light. An outer diameter of such disc for music is around 12 cm. FIG. 2 is a plane view of a main portion of a disc player and FIG. 3 is a perspective view of a internal construction thereof which includes a base 20, a feed motor 21, a pulley 23 driven by the motor 21 through a rubber belt 22, a gear 24, a pinion and rack mechanism 25, 26 as well known. In FIG. 2, a groove 3 is formed in an upper plate 2 of a container, on which a disc 1 shown by a dotted line is disposed with a small gap therebetween.
An optical pick-up 4 is provided in the groove 3 and is movable radially outwardly as to be described later. The optical pick-up 4 includes a lens 41.
The disc 1 is mounted on a turn-table 5 fixed to a rotary shaft 6 so that it is rotated with a rotation of the shaft 6.
The optical pick-up 4 includes a laser element which emitts a laser light upwardly. The laser light is collimated by the lens 41 to a thin beam with which the disc is irradiated. The laser beam reflected by a surface of the disc passes through a half mirror to a photo diode from which the signal is picked up.
When the disc 1 is mounted on the turn table 5 and the rotary shaft 6 secured thereto is rotated by such as a motor, the optical pick-up 4 approaches an initial position close to the disc 1 from its original position and emitts light. For a reproduction of music, the optical pick-up 4 moves rightwardly in FIG. 2 with keeping its close positional relation to the disc 1 and, after the reproduction completes, returns to the initial position.
When the disc 1 is rotated in a horizontal plane, the optical pick-up 4 having the lens surface 41 thereon is subjected to adhesion of dust or the like which affects a laser beam irradiation adversely. Such adhesion of dust necessarily affects a reproduced sound and, so, such dust must be removed. However, since the original position of the optical pick-up 4 when the disc 1 is stationary is around a bottom of the groove 3 in FIG. 2, it is impossible to clean the lens surface 41 without removing the upper plate 2.
Japanese Utility Model Application Laid-Open No. 57931/1987 belonging to the applicant of the present application discloses a cleaning device which makes a cleaning operation of the lens surface 41 possible with the upper plate 2 being as it is and which is shown in FIG. 4 of the present application. As shown in FIG. 4 in which the optical pick-up 4 is in a position at which the disc 1 starts to rotate, the cleaning device comprises a dummy disc 1a mounting a brush 7 thereon. The dummy disc 1a may be such one having a control signal recorded as an unacceptable duplication of an original disc. The control signal includes a synchronizing signal, a transmission channel number, an address signal and a data signal in a predetermined sequence. In such case, it is possible to use the recorded control signal effectively to be described later.
The position on the dummy disc 1a in which the brush 7 is to be mounted and the size of the brush 7 are selected such that the brush 7 covers an area on which the control signal is recorded, i.e., an area from a position P1 in which the lens 41 of the optical pick-up 4 faces to the disc at a start time of disc rotation to a position P2 at which the optical pick-up 4 should complete a readout of the control signal.
In operation, when the rotary shaft 6 associated with the turn table 5 on which the dummy disc 1a is mounted is rotated, the optical pick-up 4 in the position P1 moves from its original position vertically up to the initial position along an arrow A1. Then, the pick-up 4 moves horizontally to the position P2 along an arrow A2, at which the reading of the control signal is to be completed. The brush 7 is adapted to be in contact with the lens surface 41 of the optical pick-up 4 in this area while the optical pick-up 4 moves from the position P1 to P2, so that dust thereon if any is removed thereby. In this case, due to the presence of the brush 7, the dummy disc 1a is returned to its original position for the reason that the reading of control signal fails.
Then, the dummy disc 1a is removed and the disc 1 is set on the turn table to perform an ordinary reproduction of music. In this ordinary reproduction, the optical pick-up moves along the arrows A1, A2 and then A3, as shown.
In the conventional device as mentioned, in order to shorten a time from a setting of the disc 1 on the turn table 5 to a commencement of reproduction, a moving speed of the optical pick-up 4 along the arrow A1 has been increased. In such scheme, the lens 41 of the optical pick-up 4 may collide with the brush 7 and, when the stiffness of the brush 7 is high enough to obtain a satisfactory cleaning effect, the lens surface 41 may be damaged thereby during a repeating use thereof.